Climate change increases risk of crop slowdown in next 20 years

Jul 25, 2014

In this image, a storm looms behind wheat fields in eastern Colorado, where recurrent drought has had major impacts on agriculture over the last 15 years. Credit: UCAR, Carlye Calvin.

The world faces a small but substantially increased risk over the next two decades of a major slowdown in the growth of global crop yields because of climate change, new research finds.

The authors, from Stanford University and the National Center for Atmospheric Research (NCAR), say the odds of a major production slowdown of wheat and corn even with a warming climate are not very high. But the risk is about 20 times more significant than it would be without global warming, and it may require planning by organizations that are affected by international food availability and price.

"Climate change has substantially increased the prospect that crop production will fail to keep up with rising demand in the next 20 years," said NCAR scientist Claudia Tebaldi, a co-author of the study.

Stanford professor David Lobell said he wanted to study the potential impact of climate change on agriculture in the next two decades because of questions he has received from stakeholders and decision makers in governments and the private sector.

"I'm often asked whether climate change will threaten food supply, as if it's a simple yes or no answer," Lobell said. "The truth is that over a 10- or 20-year period, it depends largely on how fast the Earth warms, and we can't predict the pace of warming very precisely. So the best we can do is try to determine the odds."

Lobell and Tebaldi used computer models of global climate, as well as data about weather and crops, to calculate the chances that climatic trends would have a negative effect of 10 percent on yields of corn and wheat in the next 20 years. This would have a major impact on food supply. Yields would continue to increase but the slowdown would effectively cut the projected rate of increase by about half at the same time that demand is projected to grow sharply.

They found that the likelihood of natural climate shifts causing such a slowdown over the next 20 years is only 1 in 200. But when the authors accounted for human-induced global warming, they found that the odds jumped to 1 in 10 for corn and 1 in 20 for wheat.

The study appears in this month's issue of Environmental Research Letters. It was funded by the National Science Foundation (NSF), which is NCAR's sponsor, and by the U.S. Department of Energy (DOE).

More Crops Needed Worldwide

Global yields of crops such as corn and wheat have typically increased by about 1-2 percent per year in recent decades, and the U.N. Food and Agriculture Organization projects that global production of major crops will increase by 13 percent per decade through 2030—likely the fastest rate of increase during the coming century. However, global demand for crops is also expected to rise rapidly during the next two decades because of population growth, greater per-capita food consumption, and increasing use of biofuels.

Lobell and Tebaldi set out to estimate the odds that climate change could interfere with the ability of crop producers to keep up with demand. Whereas other climate research had looked at the crop impacts that were most likely, Lobell and Tebaldi decided to focus on the less likely but potentially more dangerous scenario that climate change would reduce yield growth by 10 percent or more.

The researchers used simulations available from an NCAR-based climate model (developed by teams of scientists with support from NSF and DOE), as well as several other models, to provide trends in temperature and precipitation over the next two decades for crop-intensive regions under a scenario of increasing carbon dioxide. They also used the same model simulations without human-caused increases in carbon dioxide to assess the same trends in a natural climate.

In addition, they ran statistical analyses to estimate the impacts of changes in temperature and precipitation on wheat and corn yields in various regions of the globe and during specific times of the year that coincide with the most important times of the growing seasons for those two crops.

The authors quantified the extent to which warming temperatures would correlate with reduced yields. For example, an increase of 1 degree Celsius (1.8 degrees Fahrenheit) would slow corn yields by 7 percent and wheat yields by 6 percent. Depending on the crop-growing region, the odds of such a temperature increase in the next 20 years were about 30 to 40 percent in simulations that included increases in carbon dioxide. In contrast, such temperature increases had a much lower chance of occurring in stimulations that included only natural variability, not human-induced climate change.

Although society could offset the climate impacts by planting wheat and corn in cooler regions, such planting shifts to date have not occurred quickly enough to offset warmer temperatures, the study warned. The authors also found little evidence that other adaptation strategies, such as changes in crop varieties or growing practices, would totally offset the impact of warming temperatures.

"Although further study may prove otherwise we do not anticipate adaptation being fast enough to significantly alter the near-term risks estimated in this paper," they wrote.

"We can't predict whether a major slowdown in crop growth will actually happen, and the odds are still fairly low," said Tebaldi. "But climate change has increased the odds to the point that organizations concerned with food security or global stability need to be aware of this risk."

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User comments : 45

Before the deniertards weigh in - this is a well known weakness of most plants (C3 plants), they don't do as well as the temperature rises due to the way RuBisCo gains affinity for O2 at the expense of CO2 as temp goes up. This results in less CO2 being fixed into sugars, which is bad mmmkay.

the problem with articles like this is they don't say "If temperatures rise, such and such will be affected." Instead they say, "Climate change will do such and such." So this is not a factual statement about the effect of temperature; it is implicitly stating that climate change is a fact. It is, if you will, a subliminal message.

Besides this I might add that the term "climate change" was invented because "global warming" failed so badly as a prediction. So to say that climate change will affect plants is meaningless. A change in the climate can mean anything, including a new ice age, which will surely affect plants, but in a very different way.

Back in 2009 June issue SciAm run editorial mentioning that stimulus plan would allow more science grants (good thing), but it will also increase waste and fraudulent research (not such a good thing). This reincarnation Paul R. Ehrlich idea married with "climate change" is fine example of the latter.

YAWN. The "man-made climate change" just will not go away. You can't affect earth's natural evolution, it's going to do what it wants whether man exists or not, just like it has done for millions of years. You whacked out reality-hating, science-denying climate cultists who think that communism is the only "solution", need to be put in straight jackets and locked in padded cells.

Dude, temperatures are rising, and will continue to do so. Climate change is just the "Frank Lunz-ing" of global warming, but the fact remains that our climate is warming and we (humanity) are largely at fault.

How fast are temps rising? 1K/century at best?http://wattsupwit...-update/Don't tell me this is published at the wrong website; point out which graphs are false. And no cute escalator references, if this is not too much to ask.

How fast are temps rising? 1K/century at best?http://wattsupwit...-update/Don't tell me this is published at the wrong website; point out which graphs are false. And no cute escalator references, if this is not too much to ask.

If you post it, it's bullshit. If it's from that website, it's bullshit. You are nothing but a denier troll POS that the world would be a better place without - why don't you make that happen?

The researchers used simulations available from an NCAR-based climate model

Meanwhile, in the real world, during the previous century, temperatures and CO2 increased and crop yield followed in step.

Your knowledge of plant physiology and biochemistry is about as good as your knowledge of climate - i.e. piss poor. Please, explain how crop yields of C3 plants (~95% of plant biomass) went up with temperature (I need causation, not correllation due to GM), I'm genuinely interested in your answer. Let me save you a little time though, look up RuBisCo (plant enzyme that fixes CO2 into sugar) and how its active site works with higher temps in regards O2 vs. CO2 and futile cycles. Rice is a C3 plant, as are wheat, oats, soy, cotton, etc. Corn is C4, which deal better with higher temps.

...this is a well known weakness of most plants (C3 plants), they don't do as well as the temperature rises due to the way RuBisCo gains affinity for O2 at the expense of CO2 as temp goes up. This results in less CO2 being fixed into sugars...

...this is a well known weakness of most plants (C3 plants), they don't do as well as the temperature rises due to the way RuBisCo gains affinity for O2 at the expense of CO2 as temp goes up. This results in less CO2 being fixed into sugars...

What about C4 plants?

most of our food crops (and nearly all plants) are C3... like rice, wheat, soy, oats, and potatoes along with cotton. corn is C4, as is sugar cane and will be less affected (though drought is still a problem). alternately - C4 plants explode ;)

If you know what C3 and C4 are, you might be well aware of1. Amazing natural adaptability of living organisms 2. Biotech breakthrough in last half centuryI doubt you genuinely believe what you wrote [the suggested food decrease/shortages].

If you know what C3 and C4 are, you might be well aware of1. Amazing natural adaptability of living organisms 2. Biotech breakthrough in last half centuryI doubt you genuinely believe what you wrote [the suggested food decrease/shortages].

You really are a fucking moron, aren't you? Plants have had the same problem since the time of the f'ing dinosaurs (before actually). The 'adaption' is the C4 and CAM pathways have evolved, you think plants will magically evolve a new pathway in the next 50 years? Maybe the C4 rice project will work out, maybe it won't. Either way, you're an idiot. Lower productivity of C3 plants at elevated temps has been experimentally proven over and over, and the reason is well know (and I have told you the reason).

If only you could detach yourself from rice diet, and free your overheated mind to see beyond close walls of your parents basement, you would notice that food organic structure is quite simple. They managed to manufacture artificial meat already, and who knows what would we have on the supermarket shelves tomorrow. Don't assume other science and engineering field capabilities as puny as climate "science".

Your knowledge of plant physiology and biochemistry is about as good as your knowledge of climate - i.e. piss poor...blah..blah..

--da supatard

Global yields of crops such as corn and wheat have typically increased by about 1-2 percent per year in recent decades, and the U.N. Food and Agriculture Organization projects that global production of major crops will increase by 13 percent per decade through 2030—likely the fastest rate of increase during the coming century

Supatard, if you had bothered to read the article you would have noticed the above.

Before the deniertards weigh in - this is a well known weakness of most plants (C3 plants), they don't do as well as the temperature rises due to the way RuBisCo gains affinity for O2 at the expense of CO2 as temp goes up. This results in less CO2 being fixed into sugars, which is bad mmmkay.

......then use non genetically modified plants which are well known to be more adaptive to extremes in weather.

Before the deniertards weigh in - this is a well known weakness of most plants (C3 plants), they don't do as well as the temperature rises due to the way RuBisCo gains affinity for O2 at the expense of CO2 as temp goes up. This results in less CO2 being fixed into sugars, which is bad mmmkay.

"RuBisCO catalyzes either the carboxylation or oxygenation of ribulose-1,5-bisphosphate (known as RuBP) with carbon dioxide or oxygen. What makes it unique and different to every other enzyme is the fact that it can survive on its own without the need of the plant so even if it is dead it remains and helps decomposition. This is due to it not being affected by temperature or pH. "(Wikipedia)

@Tegiri - showing more ignorance, good job. Rice is the most important staple crop in the world, dumbass.

@antiwhatever - That's in spite of temp increase - say hello to the power of GM food. And corn/maize, a C4 plant.

@benni - dumbass, I'm talking about wild type (unmodified for the ignorant), and if C3 plants didn't "adapt" out of this during periods when it was significantly warmer than projections for our future (i.e. at some time in the last ~200 million years) what makes you think they're gonna do it now? You don't have a clue what I'm talking about here, do you? C3 and C4 describe metabolic pathways in plants.

lol the three fucking stooges, all we need now is riggwhatever to complete the set.(larry, curly, moe, and shemp).

edit - @markb uh, dude, RuBisCo shows greater affinity for O2 over CO2 as temperature increases. This is a well know fact taught in any undergrad biochem class (and in a couple I took).

So to say that climate change will affect plants is meaningless. A change in the climate can mean anything, including a new ice age, which will surely affect plants, but in a very different way.

The vegetation that will be most affected is genetically modified foodstuffs, so for a time there is likely to be shortages of corn, wheat, soybeans, & a few other staples, all of which are 99% genetically modified to make them more suitable for specific climate conditions, soil, & pest conditions specific to the location in the world these are grown.

As the conditions change for which the genetically modified plant was modified, then of course it will cease to be productive until they are replaced by more adaptive plants. They can be genetically modified for the new conditions, but that takes years to do, use nonGMO & there is less concern about the adaptability of most vegetation we commonly use in our food supply system.

"Before the deniertards weigh in""If you post it, it's bullshit.""i.e. piss poor.""You really are a fucking moron, aren't you?""Either way, you're an idiot.""@Tegiri - showing more ignorance, good job""@benni - dumbass,""lol the three fucking stooges, all we need now is riggwhatever to complete the set."

@supamark23- you need to learn the language of science before trying to impress us with a litany of chemistry courses you claim to have taken. With the above kind of language I've copied you above as using, it's no wonder other posters here don't take you seriously, or take you seriously that you've really taken the chemistry courses you claim. I'm a Nuclear/Electrical Engineer.

Lobell and Tebaldi used computer models of global climate, as well as data about weather and crops, to calculate...

There's the first, and fundamental, problem: starting with bad data. The "computer models of global climate" are not accurate. Even the IPCC knows this and has documented it, though the "Summary for Policymakers" glosses over it. The Summary for Policymakers is edited and approved by politicians from member countries. The Technical Summary isn't. In the Technical Summary, pg. 64 is this graph showing how poorly the climate models perform when compared with instrument measurements of global temperatures:

I'm about to blow all of your minds, fossil fuels come from fossils. Lets add another twist, fossils are things that used to be alive. The planet looks green because by mass, plants are the main life form on this planet.

Bare with me, I know this is hard to understand. Plants get their carbon from CO2. The time of the most extensive forestation of out planet was during the Devonian and Carboniferous eras. That's where the bulk of our fossil fuels come from.

Then we burn the hydrocarbons releasing the CO2, were it is absorbed by a bunch of really smart Americans who know everything about the environment and the problem goes away forever. THANKS REPUBLICANS!

It stopped warming in 1998, something the alarmists (Malthusian leftists) did not predict and cannot explain. Now they are focused on predictions of bad consequences of warming.

It is only common sense that a warmer climate with much higher CO2, which would also have more rain, would be much better for virtually all plant life. Unfortunately the authors turn to computer models, the best example of the failure of alarmist predictions, to try to convince us that their findings would be valid and believable. I think they should have done plant experimentation instead, with temperature and CO2 variation, allowing real-world actual plant growth results to test their ideas.

Agricultural production has been soaring for 200 years. It will continue. Malthus was wrong then and his acolytes are wrong now.

@BenniI can't speak for Vietvet, but I would like to comment.You denigrate supamark for his words, but you have NO IDEA the historical context in which they are offered. Have you been watching him interact with these same people and watching how they TROLL or they can't accept empirical evidence?

Then you appeal to authority with your comment

I'm a Nuclear/Electrical Engineer

Well SOME people find it hard to believe that a Nuclear/electrical engineer would be so INEPT with a computer, and so completely PC/internet illiterate. Even my daughter (graduating spring as an electrical engineer) wondered what your issue was concerning your inability to comprehend and differentiate PM's, E-mail, MOD/Admin/server messages and the whole conversation we had. I cannot even begin to describe the names you were called over THAT one

You ignore empirical data for a BELIEF regarding the climateNOT SCIENTIFICwhat are you REALLY?

Maybe you can elaborate on why you just cast a one star for my above post? You think it's an inappropriate post?

@Bennidid you ever finally find that "CONTACT" link at the bottom of EVERY PAGE like I told you to look for?

then use non genetically modified plants which are well known to be more adaptive to extremes in weather.

ask yourself: what good would this be to us if we cannot control the current global warming issue? What would happen to US if we push ourselves into a runaway feedback mechanism that created another mass extinction?

So what? People invented fire cooking somewhere 100000 years ago, and their diet essentially hasn't been changed since then. However, like it or not, synthetic food is coming, here are numerous reports of plastic ricehttps://www.googl...tic+riceYes, anything "plastic" (or made from oil, for that matter) is anathema to certain kind of people. (Those, that happens to think that more windmills, and solar panels is a great progress). Those would be simply rendered to the footnotes of civilization, together with their beloved "organic" isles in the supermarket.

Let me describe you a genuine crisis. Imagine all farmers stopped working and stated exchanging angry messages on silly boards like this. Imagine all real scientists abandon their native fields of specialization and starting manufacturing global warming related crap studies like the one we are discussing. Then civilization is in real danger.

How fast are temps rising? 1K/century at best?http://wattsupwit...-update/Don't tell me this is published at the wrong website; point out which graphs are false. And no cute escalator references, if this is not too much to ask.

If you post it, it's bullshit. If it's from that website, it's bullshit. You are nothing but a denier troll POS that the world would be a better place without - why don't you make that happen?

"Maybe you can elaborate on why you just cast a one star for my above post? You think it's an inappropriate post? "@Bennidid you ever finally find that "CONTACT" link at the bottom of EVERY PAGE like I told you to look for?"

The return of the stooges, i get my fix by reading the comments section on each physorg climate article, cracking up at how denialists reach to new levels of dumb by every new post they make. One thing's for sure, these bunch of baboons now how to do stupid.... I'd love to see these idiots debate live television, reading their comments here is funny, but actually seeing what these morons look like would really crack me up.

However, the environment looks even worse when the so-called "Greenpeace" is around. Why? They are attempting to prevent the use of carbon dioxide, an essential material for Earth, and closing its eyes to real dangers that come with factories, such as acidic gases and an aerosol that comes out of the factory that irritate the human lungs.

Rice production is rising along with CO2. New varieties of crops will solve any decrease due to CO2 increases.

Exactly, plus moving a crop just 100 miles or so makes things 1C cooler. Farmers do this without thinking. For example the northern limit for corn growing in North America has moved north rapidly due to corn prices and farming techniques.

A 5C rise in temperatures would simply move crops around on the planet, in mostly modest ways.

Let us bow down to the great God of climate scienceAnd verily we shall take of his wordAnd dismiss all that be discovered not in thy nameThy word shall be the science, the power and the climateFor ever and ever.AmenFFS

How fast are temps rising? 1K/century at best?http://wattsupwit...-update/Don't tell me this is published at the wrong website; point out which graphs are false. And no cute escalator references, if this is not too much to ask.

Sorry but that's the wrong website. If you want to know which graph is wrong, it's ALL of them! That is a denier propaganda site paid for by dark money from the Heartland deceptiCON wingnut 501c. What you need is a real fact based website like http://climate.govThat will show you where the problems are, and it isn't for the faint of heart. 1K per century. That is under the most generous of light global warming. Most indicators are that it will be far worst, with 6K change possible by 2100. I'm very pessimistic because I don't see any cooperation from industry on the climate warming issue.

@Bennidid you ever finally find that "CONTACT" link at the bottom of EVERY PAGE like I told you to look for?

then use non genetically modified plants which are well known to be more adaptive to extremes in weather.

ask yourself: what good would this be to us if we cannot control the current global warming issue? What would happen to US if we push ourselves into a runaway feedback mechanism that created another mass extinction?

just one question here crickey ol' mate: Ever seen a differential equation you could solve?

@benniconsidering your inability to comprehend the physics behind climate change and global warming as well as other displays of ignorance here on PO... the question really should be: have YOU?

you talk big but you've offered NO proof or evidence of being educated beyond high school science, and you've displayed considerable ignorance regarding computers, and considering my daughter is right now finishing her degree as an electrical engineer, it seems especially cogent to point out that she is incredibly well versed in computers as part of her degree.

perhaps your education was pre-1890's? or are you just lying and trolling?

considering your inability to comprehend the physics behind climate change and global warming as well as other displays of ignorance here on PO... the question really should be: have YOU?

.........because I know the "physics" driving climate change is located 93 million miles away, and that is nuclear physics. You simply haven't learned the math by which to comprehend such physics or the math behind Einstein's thesis on General Relativity.........."differential equations", and you probably don't know what type. Ask your "twin", he thinks he knows, he thinks they are "different".

discouragedinMI

because I know the "physics" driving climate change is located 93 million miles away

and there is just nothing here that can affect it, huh? ROTFLMFAO! IF you had the ability to prove that, you would have taken that $30,000.oo challenge!

You simply haven't learned the math by which to comprehend such physics or the math behind Einstein's thesis on General Relativity

personal conjecture without evidenceand so far you've not shown the ability to comprehend ANY physics!

Good phishing to you too

ROTFLMFAOyou DO REALISE that if I wanted to steal your info, I would just ping your server and get your internet IP which would give me the ability to go right to your doorstep? Easy since I KNOW your login here AND when you are on

you don't have anything of value to me.

and AGAIN! MORE PROOF that you are not an electrical engineer! LOLYOU DON'T KNOW SQUAT about computers!

you DO REALISE that if I wanted to steal your info, I would just ping your server and get your internet IP which would give me the ability to go right to your doorstep? Easy since I KNOW your login here AND when you are on

Jeepers Stump, if you could do all that you would have already done it..........why get so PO'd at me just because you are so mathematically challenged.

and AGAIN! MORE PROOF that you are not an electrical engineer! LOLYOU DON'T KNOW SQUAT about c

And do you know what type of "differential equations" Einstein used in most of his thesis on General Relativity? I'll give you a hint, they are not called "different".......

And do you know what type of "differential equations" Einstein used in most of his thesis on General Relativity? I'll give you a hint, they are not called "different".......

@benni-&-the-NOOkesyou are talking about someone else, not me, stupid

if you could do all that you would have already done it

that was pretty much the point, NOOclear boy- also pointing out that you are computer illiterate, which pretty much supports the fact that you are NOT an electrical engineer, and likely not anything else you claim either

You claim that everyone here is mathematically challenged... yet you've demonstrated NOTHING yourself. You're a hypocrite & liarhttp://dialogueso...and.htmlIF you have PROOF that global warming isn't happening, you should PROVE it! take the challenge! PROVE the preponderance of empirical data is wrong!